1. Field of the Invention
The present invention generally relates to lamps and candles that burn with a characteristic color. More particularly, the present invention relates to lamps and candles that burn with a colored flame.
2. Description of the Related Art
A conventional oil lamp generally includes a vessel containing oil with a wick soaked in the oil. The wick is ignited to produce illumination from a flame that is a conventional yellow color. The precise origin of the oil lamp is obscure, but such lamps were in general use in Greece by the 4th century B.C. and centuries earlier in Egypt. The first oil lamps were open vessels made of stone, clay, bone, or shell in which fat or oil was burned. Later lamps were partially enclosed reservoirs, containing fat or oil that were provided with a small hole into which a wick of flax or cotton was set. The fuel is drawn up the wick by capillary action and burned at the end of the wick.
A colored flame candle is described in U.S. Pat. No. 4,386,904 to Miyahara et al. In order to produce vividly colored flames, instead of conventional primary combustion agents, such as paraffin and stearic acid, which produce a yellowish orange color by themselves, the primary combustion materials are used which form a colorless flame such as ethyl carbamate (urethane), dimethyl oxalate, and/or trioxane. In addition, an oxidation accelerator catalyst is absorbed on the cotton combustion wick, to result in a candle that itself burns with a strictly colorless flame. A coloring wick is separately fabricated containing a color-forming compound as well as oxidation accelerating catalyst and preferably may be coated with resin on its surface. The coloring wick is then placed adjacent the combustion wick, and a candle is formed using the aforementioned primary combustion material. One or several coloring wicks may be embedded parallel to the combustion wick or may be embedded coiled around the combustion wick.
U.S. Pat. No. 5,127,922 to Bension describes a candle that burns with a colored flame, which is free of the yellow color, usually found in the conventional paraffin candle. The candle comprises a shell made of a saturated thermoplastic material and 10-30% of a fire retardant. The fuel consists of 70-100% of a polyoxymethylene, 0-30% of a binder, and 0-20% of a solvent. The candle also comprises 1-10% of a flame-coloring agent, such as a salt or an oxide of Li, B, Na, Ca, Cu, K, Sr, In, or Ba. The candle does not require a wick.
Described herein are lamps and candles that produce colored flames of a characteristic color. A colored flame is a flame with a color different from the flame of a fuel composition burning in the absence of a color producing compound or from the color of the flame of conventional lamps or candles which is yellowish in color.
In one embodiment, a system is described that includes a lamp that uses a fuel composition that may include a liquid solvent and one or more types of metal salts. At least a portion of the metal salts may be dissolved in the solvent. The solvent and metal salts migrate through a wick that is in contact with the fuel composition during use. The fuel composition absorbed by the wick may burn with a flame of a characteristic color that differs from the color the wick would burn in the absence of metal salts.
In one embodiment, the lamp includes a receptacle for the fuel composition. A wick is placed in contact with the fuel composition in the receptacle. The wick may be composed of a natural material such as cotton or a synthetic material such as fiberglass.
In one embodiment, the solvent may include a glycol, such as propylene glycol. The solvent may also include a small amount of a simple alcohol such as methanol, ethanol, or isopropanol. The solvent may also include a small amount of a hydrochloric acid solution. A variety of metal salts may be dissolved in the solvent which when vaporized produce a flame of a characteristic color. Exemplary metal salts include, but are not limited to, boric acid, lithium hydroxide, lithium chloride, strontium nitrate, copper hydroxide, copper chloride, copper sulfate, potassium hydroxide, sodium hydroxide, and magnesium hydroxide.
In one embodiment, a colored flame candle is composed of a solvent with one or more types of metal salts dissolved in the solvent and a hardener. A wick is immersed within the candle. The candle composition is melted by the flame. The melted composition, including the metal salts, migrate up the wick and then are vaporized. The metal salts in the candle composition cause the flame to burn with a characteristic color that is different from a color the flame would burn in the absence of the metal salts.
In one embodiment, the solvent may be a glycol (e.g., propylene glycol) and the hardener may be a long chain fatty acid (e.g., stearic acid). The candle composition may possess properties similar to conventional candle wax that make it suitable as fuel for a candle. Examples of metal salts include, but are not limited to, boric acid, lithium hydroxide, lithium chloride, strontium nitrate, copper hydroxide, copper chloride, copper sulfate, potassium hydroxide, sodium hydroxide, and magnesium hydroxide. The glycol and fatty acid may be combined in relative proportions that result in a candle that ranges from soft to hard. A conventional wick may be used.